<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<title>The div should have a white filling.</title>

<style>

html, body {
  margin: 0;
  padding: 0;
}

html {
  background-color: white;
}

body {
  padding: 10px;
}

div {
  width: 50px;
  height: 50px;
  box-sizing: border-box;
  border: 1px solid black;
}

</style>

<div></div>
